INFO: task kworker/u4:3:121 blocked for more than 143 seconds.
      Not tainted 5.6.0-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/u4:3    D24312   121      2 0x80004000
Workqueue: netns cleanup_net
Call Trace:
 schedule+0xd0/0x2a0 kernel/sched/core.c:4168
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:4227
 __mutex_lock_common kernel/locking/mutex.c:1033 [inline]
 __mutex_lock+0x7ab/0x13c0 kernel/locking/mutex.c:1103
 ip_set_net_exit+0x194/0x5b0 net/netfilter/ipset/ip_set_core.c:2401
 ops_exit_list.isra.0+0xa8/0x150 net/core/net_namespace.c:186
 cleanup_net+0x511/0xa50 net/core/net_namespace.c:603
 process_one_work+0x965/0x16a0 kernel/workqueue.c:2266
 worker_thread+0x96/0xe20 kernel/workqueue.c:2412
 kthread+0x388/0x470 kernel/kthread.c:268
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Showing all locks held in the system:
4 locks held by kworker/u4:3/121:
 #0: ffff8880a9775938 ((wq_completion)netns){+.+.}-{0:0}, at: __write_once_size include/linux/compiler.h:226 [inline]
 #0: ffff8880a9775938 ((wq_completion)netns){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
 #0: ffff8880a9775938 ((wq_completion)netns){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:855 [inline]
 #0: ffff8880a9775938 ((wq_completion)netns){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:40 [inline]
 #0: ffff8880a9775938 ((wq_completion)netns){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:615 [inline]
 #0: ffff8880a9775938 ((wq_completion)netns){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:642 [inline]
 #0: ffff8880a9775938 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work+0x844/0x16a0 kernel/workqueue.c:2237
 #1: ffffc90000e27dc0 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work+0x878/0x16a0 kernel/workqueue.c:2241
 #2: ffffffff8a56a230 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0x9b/0xa50 net/core/net_namespace.c:565
 #3: ffffffff8d1f3f18 (&table[i].mutex){+.+.}-{3:3}, at: ip_set_net_exit+0x194/0x5b0 net/netfilter/ipset/ip_set_core.c:2401
1 lock held by khungtaskd/1137:
 #0: ffffffff899bbbc0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:5743
1 lock held by in:imklog/6725:
 #0: ffff8880a6d94e30 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:826
3 locks held by syz-executor.3/26409:

=============================================

NMI backtrace for cpu 0
CPU: 0 PID: 1137 Comm: khungtaskd Not tainted 5.6.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x188/0x20d lib/dump_stack.c:118
 nmi_cpu_backtrace.cold+0x70/0xb1 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x231/0x27e lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:205 [inline]
 watchdog+0xa8c/0x1010 kernel/hung_task.c:289
 kthread+0x388/0x470 kernel/kthread.c:268
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 26409 Comm: syz-executor.3 Not tainted 5.6.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:__lock_acquire+0x1b85/0x4e00 kernel/locking/lockdep.c:4314
Code: eb be 08 00 00 00 49 8d 45 3f 4d 85 ed 49 0f 49 c5 48 c1 f8 06 48 8d 3c c5 60 ad 2d 8c e8 b3 74 57 00 4c 0f a3 2d db 72 d4 0a <0f> 82 65 ee ff ff e8 20 ef 39 02 85 c0 0f 84 e9 fd ff ff 48 c7 c0
RSP: 0018:ffffc900061e6a68 EFLAGS: 00000047
RAX: 0000000000000001 RBX: 000000000000002b RCX: ffffffff81593a7d
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff8c2dad60
RBP: ffff888135eec958 R08: 0000000000000001 R09: fffffbfff185b5ad
R10: ffffffff8c2dad67 R11: fffffbfff185b5ac R12: ffff888135eec040
R13: 000000000000002b R14: 0000000000000002 R15: dffffc0000000000
FS:  00007f044c28e700(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb028de4000 CR3: 0000000135df8000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 lock_acquire+0x1f2/0x8f0 kernel/locking/lockdep.c:4923
 rcu_lock_acquire include/linux/rcupdate.h:208 [inline]
 rcu_read_lock include/linux/rcupdate.h:601 [inline]
 cond_resched_rcu include/linux/sched.h:1807 [inline]
 hash_netport4_list+0x33a/0x1270 net/netfilter/ipset/ip_set_hash_gen.h:1369
 ip_set_dump_do+0xca8/0x1970 net/netfilter/ipset/ip_set_core.c:1646
 netlink_dump+0x50b/0xf50 net/netlink/af_netlink.c:2245
 __netlink_dump_start+0x63f/0x910 net/netlink/af_netlink.c:2353
 netlink_dump_start include/linux/netlink.h:246 [inline]
 ip_set_dump+0x133/0x1a0 net/netfilter/ipset/ip_set_core.c:1705
 nfnetlink_rcv_msg+0xc83/0xf30 net/netfilter/nfnetlink.c:229
 netlink_rcv_skb+0x15a/0x410 net/netlink/af_netlink.c:2469
 nfnetlink_rcv+0x1ac/0x420 net/netfilter/nfnetlink.c:563
 netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline]
 netlink_unicast+0x537/0x740 net/netlink/af_netlink.c:1329
 netlink_sendmsg+0x882/0xe10 net/netlink/af_netlink.c:1918
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:672
 sock_no_sendpage+0xf8/0x140 net/core/sock.c:2763
 kernel_sendpage+0x82/0xd0 net/socket.c:3808
 sock_sendpage+0x8a/0xb0 net/socket.c:950
 pipe_to_sendpage+0x2aa/0x380 fs/splice.c:458
 splice_from_pipe_feed fs/splice.c:512 [inline]
 __splice_from_pipe+0x3e6/0x7b0 fs/splice.c:636
 splice_from_pipe+0xd9/0x140 fs/splice.c:671
 do_splice_from fs/splice.c:863 [inline]
 direct_splice_actor+0x115/0x160 fs/splice.c:1037
 splice_direct_to_actor+0x38c/0x980 fs/splice.c:992
 do_splice_direct+0x1b4/0x280 fs/splice.c:1080
 do_sendfile+0x555/0xc50 fs/read_write.c:1520
 __do_sys_sendfile64 fs/read_write.c:1581 [inline]
 __se_sys_sendfile64 fs/read_write.c:1567 [inline]
 __x64_sys_sendfile64+0x1cc/0x210 fs/read_write.c:1567
 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3
RIP: 0033:0x45c889
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f044c28dc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f044c28e6d4 RCX: 000000000045c889
RDX: 0000000000000000 RSI: 0000000000000007 RDI: 0000000000000008
RBP: 000000000076c040 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000100000001 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000008d6 R14: 00000000004cb7ee R15: 000000000076c04c